Monitoring and Back-Analysis in Dongjian Arch Dam

The monitoring of displacement is one of major measures to ensure the safety of an arch dam. And the back-analysis is a key link in the safety evaluation. This paper presents a case history of monitoring and back-analysis of displacement in Dongjiang Arch Dam, China. The elasticity modulus of dam foundation were determined by back-analysis of displacement for lower water level in the reservoir. The prediction of displacement of dam was compared with the results of monitoring. The suggested procedure of 3D finite element computation coupling solid and temperature stresses can be used for other types of rock engineering

Systematic study on the influence of particle size on the Cytotoxicity of nanoparticles

The study of size effects on the cytotoxicity of poly(d,l-lactide-co-glycolide acid) (PLGA) and titanium dioxide (TiO2) nanoparticles was reported in this thesis. The main objective of this study is to investigate how particle size can influence the cytotoxicity of PLGA and TiO2 nanoparticles, and to uncover the mechanism behind such toxic effects. We investigated various cytotoxicity parameters, including cell viability, generation of reactive oxygen species (ROS), mitochondrial depolarization, plasma membrane leakage, increased intracellular calcium concentration and inflammation response, to comprehensively understand the toxicity of different sized nanoparticles after cells were incubated with these nanoparticles for 24 h. Our current results show that PLGA and TiO2 nanoparticles could trigger size-dependent cytotoxicity to both RAW264.7 cells and BEAS-2B cells. The increased cytotoxicity observed from smaller nanoparticles with larger specific surface area could be explained from their surface area-dependent interactions with biomolecules. TiO2 nanoparticles could also trigger size- and surface area- dependent phototoxicity. The higher generation of hydroxyl radicals could be the major reason for the higher phototoxicity of TiO2 nanoparticles with smaller particle size and/or larger surface area. Surface coating of TiO2 nanoparticles with poly (ethylene-alt-maleic anhydride) (PEMA) and chitosan could reduce phototoxicity of TiO2 nanoparticles, by hindering adsorption of biomolecules and generation of hydroxyl radical (•OH) during photoactivation. Presence of pre-adsorbed extracellular proteins was also found to decrease toxic effects of TiO2 particles as compared to conditions without extracellular proteins. These results also suggest that surface area, a size related factor, could be a paradigm to predict the cytotoxicity of PLGA and TiO2 nanoparticles. However, this study does not overlook the importance of some other of factors such as surface functional group, which worth further exploration in future work.DOCTOR OF PHILOSOPHY (MSE

Drug-Induced Nephrotoxicity: Clinical Impact and Preclinical in Vitro Models

10.1021/mp400720wMOLECULAR PHARMACEUTICS1171933-1948United State

Nanoparticle-assay marker interaction: effects on nanotoxicity assessment

Protein-based cytotoxicity assays such as lactate dehydrogenase (LDH) and tumor necrosis factor-alpha (TNF-α) are commonly used in cytotoxic evaluation of nanoparticles (NPs) despite numerous reports on possible interactions with protein markers in these assays that can confound the results obtained. In this study, conventional cytotoxicity assays where assay markers may (LDH and TNF- α) or may not (PicoGreen and WST-8) come into contact with NPs were used to evaluate the cytotoxicity of NPs. The findings revealed selective interactions between negatively charged protein assay markers (LDH and TNF- α) and positively charged ZnO NPs under abiotic conditions. The adsorption and interaction with these protein assay markers were strongly influenced by surface charge, concentration, and specific surface area of the NPs, thereby resulting in less than accurate cytotoxic measurements, as observed from actual cell viability measurements. An improved protocol for LDH assay was, therefore, proposed and validated by eliminating any effects associated with protein–particle interactions. In view of this, additional measures and precautions should be taken when evaluating cytotoxicity of NPs with standard protein-based assays, particularly when they are of opposite charges.ASTAR (Agency for Sci., Tech. and Research, S’pore

Size influences the cytotoxicity of poly (lactic-co-glycolic acid) (PLGA) and titanium dioxide (TiO2) nanoparticles

The aim of this study is to uncover the size influence of poly (lactic-co-glycolic acid) (PLGA) and titanium dioxide (TiO2) nanoparticles on their potential cytotoxicity. PLGA and TiO2 nanoparticles of three different sizes were thoroughly characterized before in vitro cytotoxic tests which included viability, generation of reactive oxygen species (ROS), mitochondrial depolarization, integrity of plasma membrane, intracellular calcium influx and cytokine release. Size-dependent cytotoxic effect was observed in both RAW264.7 cells and BEAS-2B cells after cells were incubated with PLGA or TiO2 nanoparticles for 24 h. Although PLGA nanoparticles did not trigger significantly lethal toxicity up to a concentration of 300 μg/ml, the TNF-α release after the stimulation of PLGA nanoparticles should not be ignored especially in clinical applications. Relatively more toxic TiO2 nanoparticles triggered cell death, ROS generation, mitochondrial depolarization, plasma membrane damage, intracellular calcium concentration increase and size-dependent TNF-α release, especially at a concentration higher than 100 μg/ml. These cytotoxic effects could be due to the size-dependent interaction between nanoparticles and biomolecules, as smaller particles tend to adsorb more biomolecules. In summary, we demonstrated that the ability of protein adsorption could be an important paradigm to predict the in vitro cytotoxicity of nanoparticles, especially for low toxic nanomaterials such as PLGA and TiO2 nanoparticles.Accepted versio

An Efficient Row Key Encoding Method with ASCII Code for Storing Geospatial Big Data in HBase

Recently, increasing amounts of multi-source geospatial data (raster data of satellites and textual data of meteorological stations) have been generated, which can play a cooperative and important role in many research works. Efficiently storing, organizing and managing these data is essential for their subsequent application. HBase, as a distributed storage database, is increasingly popular for the storage of unstructured data. The design of the row key of HBase is crucial to improving its efficiency, but large numbers of researchers in the geospatial area do not conduct much research on this topic. According the HBase Official Reference Guide, row keys should be kept as short as is reasonable while remaining useful for the required data access. In this paper, we propose a new row key encoding method instead of conventional stereotypes. We adopted an existing hierarchical spatio-temporal grid framework as the row key of the HBase to manage these geospatial data, with the difference that we utilized the obscure but short American Standard Code for Information Interchange (ASCII) to achieve the structure of the grid rather than the original grid code, which can be easily understood by humans but is very long. In order to demonstrate the advantage of the proposed method, we stored the daily meteorological data of 831 meteorological stations in China from 1985 to 2019 in HBase; the experimental result showed that the proposed method can not only maintain an equivalent query speed but can shorten the row key and save storage resources by 20.69% compared with the original grid codes. Meanwhile, we also utilized GF-1 imagery to test whether these improved row keys could support the storage and querying of raster data. We downloaded and stored a part of the GF-1 imagery in Henan province, China from 2017 to 2018; the total data volume reached about 500 GB. Then, we succeeded in calculating the daily normalized difference vegetation index (NDVI) value in Henan province from 2017 to 2018 within 54 min. Therefore, the experiment demonstrated that the improved row keys can also be applied to store raster data when using HBase

Ligustrum robustum Intake, Weight Loss, and Gut Microbiota: An Intervention Trial

Ligustrum robustum (LR) shows antiobesity effects in animal studies. However, little is known about the effect on human. The present study aimed to investigate the effect of LR intake on weight change in obese women and the role of gut microbiota. Thirty overweight and obese female participants (BMI ≥24 kg/m2) were recruited in the current study. The participants drank LR 10g/d for 12 wks. Their body composition and related biomarkers were assessed. Alterations of the gut microbiota were analyzed using 16S rRNA sequencing. The primary outcome was the change in body weight. LR intake resulted in 2.5% weight loss over 12 wks (P<0.01). Change in body fat at 12 wk was -1.77 ± 1.19 kg (P<0.01). In addition, decreased Firmicutes-to-Bacteroidetes ratio (P=0.03), increased richness (the ACE estimator, P<0.01; the Chao1 estimator, P<0.01), and altered representative taxa of the gut microbiota were observed. Bacteroidaceae, Bacteroides, Bacilli, and Lactobacillales were higher while Ruminococcaceae, Enterobacteriaceae, Enterobacteriales, Lachnospiraceae, Clostridia, and Clostridiales were lower at 12 wk. Moreover, LR intervention decreased fasting glucose (P<0.01), serum leptin (P<0.01), and IL8 (P=0.02) and increased HOMA-β (P<0.01). LR intervention moderately decreased the body weight in overweight and obese women and such effect might be due to modulation of gut microbiota

Specific surface area of titanium dioxide (TiO2) particles influences cyto- and photo-toxicity

The aim of this study is to examine how different specific surface areas of similar-sized titanium dioxide (TiO2) particles could influence both cytotoxicity and phototoxicity. TiO2 particles of different specific surface areas were compared for their toxic effects on RAW264.7 cells in the absence and presence of UV light. From the results, TiO2 particles with larger specific surface area were found to induce higher cyto- (UV absent) and photo-toxicity (UV activated) to cells after 24 h incubation. The observed cytotoxicity from TiO2 particles with larger surface area could be explained from their interactions with biomolecules. Upon photoactivation, a larger number of hydroxyl radicals were detected from TiO2 particles with larger surface area, again suggesting a surface area dependent phototoxic effect. On the other hand, pre-adsorbing TiO2 particles with extracellular proteins were found to decrease toxicity effects.Accepted versio

Size of TiO2 nanoparticles influences their phototoxicity : an in vitro investigation

To uncover the size influence of TiO2 nanoparticles on their potential toxicity, the cytotoxicity of different-sized TiO2 nanoparticles with and without photoactivation was tested. It was demonstrated that without photoactivation, TiO2 nanoparticles were inert up to 100 μg/ml. On the contrary, with photoactivation, the toxicity of TiO2 nanoparticles significantly increased, which correlated well with the specific surface area of the particles. Our results also suggest that the generation of hydroxyl radicals and reactive oxygen species (ROS)-mediated damage to the surface-adsorbed biomolecules could be the two major reasons for the cytotoxicity of TiO2 nanoparticles after photoactivation. Higher ROS generation from smaller particles was detected under both biotic and abiotic conditions. Smaller particles could adsorb more proteins, which was confirmed by thermogravimetric analysis. To further investigate the influence of the generation of hydroxyl radicals and adsorption of protein, poly (ethylene-alt-maleic anhydride) (PEMA) and chitosan were used to coat TiO2 nanoparticles. The results confirmed that surface coating of TiO2 nanoparticles could reduce such toxicity after photoactivation, by hindering adsorption of biomolecules and generation of hydroxyl radical (·OH) during photoactivation.Accepted versio